The present invention relates generally to optical devices as well as methods for applying treatment radiation to the eye, and more particularly, to such devices and methods for applying treatment radiation to the retina.
Retinal laser photocoagulation is one of the most commonly applied treatment modalities. To achieve photocoagulation, a single laser pulse of green wavelength (typically at a wavelength of 514 nm or 532 nm) can be applied to the retina such that the light is absorbed and converted to heat by compact granules of melanin (melanosomes) that are located in retinal pigment epithelial (RPE) cells. As the duration of the laser pulse is typically in a range of 50 ms to 200 ms, the generated heat diffuses from those absorbers to other structures, leading to thermal coagulation of the retina. The retinal photocoagulation can be utilized in treatment of retinal diseases where scar formation and/or high radiant exposure are required (e.g., retinal detachment, diabetic retinopathy).
The retinal photocoagulation, however, can cause coagulation of photoreceptors, thus leading to blind spots and loss of visual sense. As such, this treatment modality is not suitable for application to the macula, especially the fovea. To remedy this shortcoming, selective photocoagulation of RPE cells by employing short laser pulses was developed as a therapeutic modality for those retinal diseases that are believed to be mainly caused by a dysfunction of the RPE. This treatment modality, commonly known as selective retinal therapy (SRT), uses short laser pulses to target RPE cells while preserving the adjacent photoreceptors in the neurosensory retina.
Although considerable progress has been made in the above techniques and in the design of optical devices for performing them, a need still exists for enhanced optical devices and methods for performing photocoagulation as well as selective targeting of RPE cells.
There is also a need for such optical devices and methods that provide more efficient ways of applying those treatment modalities. Further, there is a need for such devices that can be readily configured for application of one treatment modality or the other.